PLAYTEX AI Normal Map vs Bump Map evidence pair

Files:
- playtex-milled-clay-bump-512.png: 512 x 512 linear grayscale bump/height signal
- playtex-milled-clay-normal-opengl-512.png: 512 x 512 OpenGL Y+ tangent-space normal map
- evidence-manifest.json: exact generation settings, measurements, hashes, and limitations

Both maps describe the same synthetic milled-clay relief at the same 3.4 slope scale.
Import both as numeric/linear data. Test normal Y convention in the destination renderer.
Neither file changes geometry or silhouette by itself.
